MARSH HARBOUR, BAHAMAS - Debris extended for miles and floods covered much of the Bahamas in the wake of Hurricane Dorian, in what the archipelago's prime minister called one of the worst disasters to ever strike the island nation.

Emergency workers struggled to reach victims as search and rescue operations continued into Wednesday and the scope of the damage and humanitarian crisis unfolded.

"We are in the midst of one of the greatest national crises in our country's history," Bahamas Prime Minister Hubert Minnis told a news conference. "No effort or resources will be held back."

News media reported early on Wednesday that some storm victims remained stuck on rooftops, waiting for rescue. The official death count of seven is expected rise in the coming days.

"We can expect more deaths to be recorded. This is just preliminary information," Minnis told a news conference.

"Marsh Harbor has suffered, I would estimate, in excess of 60 percent damage to their homes," Minnis said, referring to the port on Great Abaco.

"The Mud, as we know, has been completely destroyed or decimated," he said referring to a shantytown known as the Mud and the Peas.

Aerial video of the Bahamas' Great Abaco Island showed miles of flooded neighborhoods, pulverized buildings, upturned boats and shipping containers scattered like toys. Many buildings had walls or roofs partly ripped off.

"Victims are being loaded on flatbed trucks across Abaco," said one Twitter poster with the handle @mvp242, describing a rain-blurred photograph of limp bodies strewn across a truck bed. Other Twitter messages said whole communities were swept away.

Dorian's winds had diminished to a Category 2 storm on the five-step Saffir-Simpson intensity scale, the hurricane grew in size and picked up speed.

Forecasters said it would come dangerously close to Florida's east coast on Wednesday, where more than a million people have been ordered evacuated.

Dorian packed sustained winds of 105 miles per hour and was moving north-northwest at 8 mph, as it churned about 90 miles east of Daytona Beach, Florida, the NHC said in a 5 a.m. EDT (0900 GMT) advisory.

"On this track, the core of Hurricane Dorian will move dangerously close to the Florida east coast and the Georgia coast through tonight," a 5 a.m. NHC advisory said.

Hurricane-force winds had expanded to 60 miles from the storm's core. "Dorian is expected to remain a powerful hurricane during the next couple of days," the NHC said.

Heavy rains and storm surge waters moving inland could cause life-threatening flash floods, the NHC said. The risk extended from Jupiter, Fla., to Surf City, N.C. Tornadoes are possible along the Florida coast until tonight, with the risk later moving to Georgia and South Carolina. -Reuters